1. Field of the Invention
This invention relates to a method of determining the thickness of organic films using x-rays.
2. Prior Art Statement
In recent years, when making various electronic materials, optical materials, magnetic materials and the like into devices, the form of the thin film is widely used because they can be subjected to fine processing, are readily laminated to give them complex functions and other reasons.
Methods used to fabricate such thin films include vacuum deposition, molecular-beam epitaxy, sputtering, chemical vapor deposition, the Langmuir-Blodgett method and others, but regardless of the method used, control of the film thickness at the molecular and atomic level is required to fabricate high-performance devices. To this end, the development of accurate techniques for determining the thickness of the film during fabrication and after fabrication is vital.
Methods of film thickness determination which are known in the prior art include the use of a quartz oscillator for measuring the thickness of films during fabrication and the use of a stylus instrument or ellipsometry to measure the films after fabrication.
A thin film may be deposited on a quartz oscillator, whereby the thickness of the film may be calculated from changes in the frequency of the oscillator caused by the increase in weight due to the deposited film. However, this method is limited to thin films deposited on oscillators and moreover, the value obtained is an average over the entire upper surface of the oscillator so accurate measurement of local film thicknesses is impossible with this method.
A stylus instrument may be used to measure the thickness of a film from the deflection of the stylus tip when put into contact with a sample of the film. However, the high stylus pressure can easily damage the sample, so this method is not suited to soft materials.
Ellipsometry is a viable non-contact method of film thickness determination, but the film thickness cannot be accurately evaluated without knowing the absorbance and index of refraction of the sample with respect to the light used.
The various problems with conventional methods of determining film thickness, as described above, have created great demand for the development of methods of easily determining the thickness of organic films.
The present invention came about in light of the above, and its object is to provide a method of determining the thickness of organic films using x-rays which is able to measure film thickness with a precision on the .ANG. order even during the fabrication of the film, without making contact with the film sample.